(1) Field of the Invention
This invention relates to the fabrication of integrated circuit devices and more particularly to a method of fabricating high density dynamic random access memory (DRAM) devices and the like.
(2) Description of the Prior Art
As DRAMs are scaled down in dimensions, there is a continuous challenge to maintain a sufficiently high stored charge per capacitor unit area. In order to construct high density DRAMs in a reasonable sized chip area, the cell structures have to change from the conventional planar-type capacitors to either trench capacitors or stack capacitors, in particular beyond the 4 Mbit DRAM era.
Recently a new concept has been advanced which calls for roughening the polycrystalline silicon surface of the capacitor electrode to increase the surface area. Several techniques for achieving a roughened surface of a polycrystalline silicon electrode layer have been suggested in U.S. Pat. No. 5,110,752 by C. L. Lu, and in technical papers by M. Sakao et al entitled "A CAPACITOR-OVER-BIT-LINE (COB) CELL WITH A HEMISPHERICAL-GRAIN STORAGE NODE FOR 64 Mb DRAMs" in IEDM 1990 TECHNICAL DIGEST pages 655-658; M. Yoshimaru et al entitled "RUGGED SURFACE POLY-SI ELECTRODE AND LOW TEMPERATURE DEPOSITED SILICON NITRIDE FOR 64 MBIT AND BEYOND STC DRAM CELL" in IEDM 1990 TECHNICAL DIGEST pages 659-662; and Pierre C. Fazan et al entitled "ELECTRICAL CHARACTERIZATION OF TEXTURED INTERPOLY CAPACITORS FOR ADVANCED STACKED DRAMs" in IEDM 1990 TECHNICAL DIGEST pages 663-666.